Radio frequency energy barrier material



April 7, 1970 J. H. M ADAMS 3,505,463

I RADIO FREQUENCY ENERGY BARRIER MATERIAL Filed April 8, 1968 2 [HEIGHTI $I?S U L A T IN Z; OR

Am 4 I4 FIG. 3A FIG. I CONDUCTIVE OR INSULATING 9 CONDUCTIVE FIG. 3B ORINSULATING 7 3 I I4 CONDUCTIVE OR INSULATING I2 I8 FIG. 3C

FIG. 6

CONDUCTIVE OR INSULATING James H. McAdcIms,

INVENTOR.

BY f

United States Patent O 3,505,463 RADIO FREQUENCY ENERGY BARRIER MATERIALJames H. McAdams, Huntsville, Ala., assignor to the United States ofAmerica as represented by the Secretary of the Army Filed Apr. 8, 1968,Ser. No. 719,590 Int. Cl. F16j 15/12; Hk 9/00 US. Cl. 174-35 3 ClaimsABSTRACT OF THE DISCLOSURE A configuration of electrical conducting,flexible wires or members arranged to have a height, width, and length.The barrier material being inserted between two conducting surfacesforming portions of an RF. energy barrier enclosure.

DEDICATORY CLAUSE The invention described herein may be manufactured,used, and licensed by or for the Government for governmental purposeswithout the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION Shielding devices for covering openings inthe past have been in the form of conventional door structures and havenot been sufiiciently effective since these doors have failed to providea complete shield for the opening. The reasons for this is that unlesone makes the door fit within very close tolerances, a gap or intersticewill occur, and electromagnetic energy may pass therethrough. Further,the joining of any two surfaces, such as connecting flanges inwaveguides, has the gap problem. There is, therefore, a need for thepresent invention which fills these gaps with an RF. barrier materialwhile at the same time allowing the surfaces to be made at normal oreven at large tolerances.

SUMMARY OF THE INVENTION The RF. energy barrier material in oneembodiment is a wire which is wound, sewn, or formed into an essentiallyrectangular or coil shape wherein the individual turns of the wire aremade to lie side by side. This will give the material height, width, andlength dimensions. In another embodiment, rings or cups placed side byside at one or more edges of a core could be used. The barrier materialcan be used by itself by placing it in a slot or trough which is formedin the door of wall of the enclosure to be shielded. The barriermaterial can also be wound around, sewn into, or clipped onto a flexiblecore. The core can be made of insulating or conducting material whichmay have a greater or lesser resiliency than that of the barriermaterial. The purpose of the invention is to provide an electricalconducting path between two surfaces of an enclosure used to restraintransmission of radio frequency energy. The two surfaces generally beingin imperfectelectrical contact and mechanical fit. The barrier materialis resilient and arranged so that each turn has essentially anindependent action in conforming mechanically to variations in thespacing of the surfaces of the enclosure. Therefore, it permits each ofthe closely spaced turns to electrically contact the surfaces andcomplete an electrical circuit. This reduces the space between thesurfaces through which the electromagnetic energy can pass.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a diagrammaticrepresentation of one embodiment of the invention;

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FIGURE 2 is a diagrammatic showing of the use of the embodiment ofFIGURE 1 between two surfaces;

FIGURES 3A-C all show possible end views of embodiments such as thatshown in FIGURE 1;

FIGURE 4 shows the use of the invention in a slot contained in one ofthe two surfaces;

FIGURE 5 is a diagrammatic representation of another embodiment of theinvention;

FIGURE 6 is a showing of a possible end view of the embodiment shown inFIGURE 5; and

FIGURE 7 shows the use of the embodiment shown in FIGURE 5 in a slotcontained in one of two surfaces.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGURE 1 shows an electricallyconductive material 1 in the shape of a wire, such as a copper wire,which is bent into an essentially rectangular shape. The turns are shownfar apart in FIGURE 1 so as to show the details. In the actualembodiment all the turns will lie side by side. This will give the wireheight, width, and length dimensions. The barrier material 3 being madeof a wire or wire-like material will be flexible, and when it is placedbetween two surfaces 4 and 5, as shown in FIGURE 2, it will make contactwith both surfaces all along its length without being a perfect fit.

The wire 1 of the material 3 can be shaped into a rectangular shape, asshown in FIGURE 3A, or it could contain one or two indentations, asshown in FIGURES 3B and 3C. Indentations could also be formed in theother sides of the rectangle as shown in FIGURE 4. .These indentationsserve to specifically locate the points at which electrical contact ismade and/or to modify or relocate the area in which resilience isexperienced. The indentations further provide areas where contactmembers other than a plane surface may be utilized. FIGURE 4 shows onepossible protruding surface, that being a round rod 7 which is attachedto or is a part of a door or wall 9. Other protruding shapes such astriangular, trapezoidal, etc. could be used for the rod 7. The othersurface 10 has a slot or trough 12 in which barrier material 3 isfitted. For details of how the barrier material may be used in a slot ortrough, see US. Patent No. 3,296,356 which was issued to applicant onJanuary 3, 1967.

A core 14, seen in FIGURES 3A and 3C, of insulating or conductingmaterial such as rubber or steel wool may be inserted within the openingof the barrier material, or the barrier material could be formed aroundthe core. The core may have a greater or lesser resiliency than that ofthe barrier material, and -it may have other desirable features. Thecore may fit only within the barrier material (FIGURE 3A), or it mayencompass a portion of the turns of the wire (FIGURE 3C). The core can,of course, be made any configuration and have any properties which maybe desired by one skilled in the art.

If a core is to be used, then the wire may be sewn or clipped in thecore, or the core could be formed about the wire. This is shown inFIGURES 5-7. In FIGURE 5, rings or cups 16 are clipped onto one edge ofthe core 18. On the other edge of the core is a wire 20 which is sewn inthe core. Wire 20 will be in the form of a coil or spiral after it issewn in the core. The rings and the turns or loops of the wire are shownfar apart in FIGURE 5 for clarity; however, in the actual embodimentthey will be placed side by side to again form a barrier material havingthree dimensions. Either one or both edges of the core may have thebarrier material. Where both edges are used, the device may be as shownin FIGURE 5, or both edges of the core may have the rings, also bothedges may have the coil configuration. In these embodiments, additionalresiliency and surface conformance is achieved when a protruding contactmember 22 is used as shown in FIG- URE 7. Additional contact points arealso achieved when any of the embodiments are installed in a slot,groove, trough, or device 24 which encloses the barrier material onthree sides as shown in FIGURE 7.

In the embodiments of this invention, the conductors are arranged atright angles to the longitudinal axis of the barrier material. By thisarrangement, the shortest possible conducting path is presented to anyinduced electrical current. Because of the numerous closely spacedindividually respondent, resilient, springy, electrical contacts, theelectrical resistance path between the two conducting surfaces isreduced Without a necessity for a high degree of smoothness or alignmentof the two surfaces when closed together.

I claim:

1. A system comprising a core means having at least first and secondedges, two electrically conductive wirelike means attached to the edgesof the core means, said wire-like means being in the configuration of aplurality of rings clipped onto the core means and positioned side byside so as to present height, width, and length dimensions, one of thewire-like means being attached to the first edge of said core means, theother wire-like means being attached to the second edge of said coremeans, first and second surfaces which are to be placed in electricalcontact with each other so as to prevent the passage of electromagneticenergy therebetween, a trough positioned on said first surface and inelectrical contact therewith, said wire-like means being positioned insaid trough and ber positioned on said second surface and in electricalcontact therewith; and said contact member 'being in con- 10 tivewire-like material which is in the configuration of a 15 and a flexiblecore means which is positioned within said turns.

References Cited UNITED STATES PATENTS 1,733,880 10/1929 Hurxthal 277235XR 2,084,523 6/1937 Crawford. 1, 2,469,474 5 1949 Perry. 3,126,440 3/1964 Goodloe. 3,259,406 7/ 1966 Kish.

25 FOREIGN PATENTS 871,176 3/1953 Germany.

DARRELL L. CLAY, Primary Examiner 0 Us. (:1. X.R.

